1. Field of the Invention
The present invention relates to an apparatus and method of mounting an antenna on a pole and, in particular, concerns an apparatus for mounting one or more antenna members, each having one or more antenna elements, on a pole in an aesthetically pleasing fashion.
2. Description of the Related Art
Mobile communication devices such as cellular telephones, pagers and the like are now commonly used throughout most of the industrialized world. These types of devices require that there be base stations with associated antenna assemblies positioned throughout the operational area of the mobile devices. Communication signals can then be passed between the mobile devices and a fixed communication system, e.g., the publicly switched telephone network. Increasingly, mobile communication devices are being used in urban and residential areas which require that base stations also be positioned in these areas. One difficultly that occurs, especially when base stations are placed in residential areas, is that large, often unsightly antenna structures, which form a necessary component of the typical base station, must also be placed in these areas.
A typical antenna structure used for cellular telephone communications is comprised of a vertical tower or pole on top of which sits an array of antennas. The antenna array is usually designed to provide 360.degree. coverage so that communication signals can be transmitted to, and received from, mobile units located in any direction from the base station. One common manner of providing the 360.degree. coverage is to assign one or more receive antennas and one or more transmit antennas to carry the communication signals between the base station and the mobile units located within a particular arc of directions. For example, one common scheme is to assign three groups of directional transmit and receive antennas to each cover a 120.degree. arc to thereby provide 360.degree. of communication coverage.
In these types of prior art antenna assemblies, there are generally at least two receive antennas which must be positioned a certain distance from each other to avoid interference between communications carried by each antenna. In fact, the receive antennas covering a single 120.degree. arc quite often have to be positioned more than 15 feet apart to optimize the signal carrying capacity of these antennas. This separation of the receive antennas requires that the antenna tower include a horizontal structure positioned on the top of the tower so that the receive antennas can be horizontally spaced from each other. Unfortunately, this horizontal structure is generally very heavy and requires that the tower or pole supporting the antenna array be large enough to support, not only the weight of the antennas, but also the weight of the horizontal support structure. Consequently, the typical prior art antenna tower is generally very large and obtrusive due to the horizontal structure and multiple antennas positioned on top of the tower.
It can be appreciated that installation of an antenna tower of this type can be very complex and expensive. Specifically, a pole or tower of sufficient strength and size to support the horizontal support structure and the antennas must first be erected. Generally, these towers are either large diameter poles or assembled multi-piece towers like those used for high tensions transmission lines. Once the tower is erected, the horizontal structure then has to be constructed and attached to the tower. Often this can only be accomplished once the tower has been erected which requires that the workers assemble the horizontal support structure and mount the antennas while suspended up in the air adjacent the top of the tower.
Further, once the horizontal support structure and antennas are mounted, it is difficult to reorient the position of the antennas. Ideally, a directional antenna is exactly positioned so that its transmission or reception capabilities are maximized. Often it is necessary to reorient the antenna to maximize its capabilities as a result of changes in the environment surrounding the antenna tower. For example, the addition of other communication devices in the vicinity of the antenna tower may create communication difficulties for the antenna tower which could be overcome by repositioning or reorienting the antennas. The complexity and size of the horizontal support structure makes reorienting the antennas a difficult task.
Furthermore, the antenna towers of the prior art are also viewed as an eyesore in residential communities. The size of the tower and the horizontal structure on the top of the tower produces a very obtrusive visual appearance which is generally inconsistent with the appearance of other objects positioned in the residential area, such as traffic lights, street lights and the like. Consequently, many governmental agencies have begun to severely limit the ability of cellular communication companies to install these antenna towers especially in or near residential areas.
Hence, there is a need in the prior art for an antenna mounting apparatus or system which allows directional antennas to be easily mounted on the top of poles, so as to provide communications over a desired arc, without resulting in antenna towers having an unsightly appearance. Further, there is also a need in the prior art for an antenna mounting system which will allow for easy installation, orientation and adjustment of an array of antennas on existing poles.